From 4439162fea40ac151e493dd5e1f86f6e3acc266c Mon Sep 17 00:00:00 2001
From: Swung0x48 <swung0x48@outlook.com>
Date: Thu, 2 Jul 2026 19:22:39 +0800
Subject: [PATCH] [Fix] (MG_Impl/GLImpl): refresh generated mipmap storage
 [skip ci]

---
 .../MG_Backend/DirectVulkan/DirectVulkan.cpp    |  4 +++-
 MobileGL/MG_Impl/GLImpl/Texture/GL_Texture.cpp  | 17 +++++++++++++++--
 2 files changed, 18 insertions(+), 3 deletions(-)

diff --git a/MobileGL/MG_Backend/DirectVulkan/DirectVulkan.cpp b/MobileGL/MG_Backend/DirectVulkan/DirectVulkan.cpp
index 2e3f0463..790e11b0 100644
--- a/MobileGL/MG_Backend/DirectVulkan/DirectVulkan.cpp
+++ b/MobileGL/MG_Backend/DirectVulkan/DirectVulkan.cpp
@@ -614,7 +614,9 @@ namespace MobileGL::MG_Backend::DirectVulkan {
                                           srcWidth, srcHeight, srcDepth);
     }
     void GenerateMipmap(GLenum target) {
-        MOBILEGL_ASSERT(pVulkanRenderer, "DirectVulkan::GenerateMipmap called with null VulkanRenderer");
+        if (!pVulkanRenderer) {
+            return;
+        }
         MOBILEGL_ASSERT(MG_State::pGLContext, "DirectVulkan::GenerateMipmap called with null GL context");
         pVulkanRenderer->GenerateMipmap(target);
     }
diff --git a/MobileGL/MG_Impl/GLImpl/Texture/GL_Texture.cpp b/MobileGL/MG_Impl/GLImpl/Texture/GL_Texture.cpp
index 1906fa19..23de86d5 100644
--- a/MobileGL/MG_Impl/GLImpl/Texture/GL_Texture.cpp
+++ b/MobileGL/MG_Impl/GLImpl/Texture/GL_Texture.cpp
@@ -233,7 +233,7 @@ namespace MobileGL::MG_Impl::GLImpl {
 
             const SizeT bytesPerTexel = baseByteSize / baseTexelCount;
             const Uint requiredLevelCount = ComputeFullMipmapLevelCount(baseTexelSize);
-            for (Uint level = existingLevelCount; level < requiredLevelCount; ++level) {
+            for (Uint level = 1; level < requiredLevelCount; ++level) {
                 const IntVec3 levelTexelSize = ComputeMipmapTexelSize(baseTexelSize, level);
                 const SizeT levelByteSize = bytesPerTexel * static_cast<SizeT>(levelTexelSize.x()) *
                                             static_cast<SizeT>(levelTexelSize.y()) *
@@ -244,6 +244,12 @@ namespace MobileGL::MG_Impl::GLImpl {
             return true;
         }
 
+        void EnsureGeneratedMipmapStorageAllocated(MG_State::GLState::TextureObjectMipmap& texture) {
+            for (const TextureUploadTarget uploadTarget : texture.GetUploadTargets()) {
+                EnsureGeneratedMipmapStorageAllocated(texture, uploadTarget);
+            }
+        }
+
         Bool IsMultisampleTextureTarget(TextureTarget target) {
             return target == TextureTarget::Texture2DMultisample ||
                    target == TextureTarget::Texture2DMultisampleArray;
@@ -3043,6 +3049,7 @@ namespace MobileGL::MG_Impl::GLImpl {
         if (textureObject) {
             auto* mipmapTexture = dynamic_cast<MG_State::GLState::TextureObjectMipmap*>(textureObject.get());
             MOBILEGL_ASSERT(mipmapTexture != nullptr, "GenerateMipmap requires mipmap texture storage.");
+            EnsureGeneratedMipmapStorageAllocated(*mipmapTexture);
         }
         GenerateMipmap_Backend(target);
     }
@@ -3053,7 +3060,13 @@ namespace MobileGL::MG_Impl::GLImpl {
             auto* mipmapTexture = dynamic_cast<MG_State::GLState::TextureObjectMipmap*>(textureObject.get());
             MOBILEGL_ASSERT(mipmapTexture != nullptr, "GenerateTextureMipmap requires mipmap texture storage.");
         }
-        WithTemporarilyBoundNamedTexture(textureObject, [&](GLenum target) { GenerateMipmap_Backend(target); });
+        WithTemporarilyBoundNamedTexture(textureObject, [&](GLenum target) {
+            if (textureObject) {
+                auto* mipmapTexture = dynamic_cast<MG_State::GLState::TextureObjectMipmap*>(textureObject.get());
+                EnsureGeneratedMipmapStorageAllocated(*mipmapTexture);
+            }
+            GenerateMipmap_Backend(target);
+        });
     }
 
     void GetTexImage(GLenum target, GLint level, GLenum format, GLenum type, GLvoid* pixels) {